The present invention relates to a multi-speed power transmission and especially to a multiple gear transmission having constantly meshed gears.
In a typical road vehicle, power is conveyed from an engine to the rear or front wheels by a transmission system. The transmission system includes a fluid or dry plate clutch, a transmission housing or gear box, and a final drive system. Clutches typically are formed of multiple plates which can be moved in and out of surface contact with each other to thereby engage or disengage the input shaft to the transmission from a power source, such as a vehicle engine. In a typical manual transmission, means have been employed for moving predetermined gears of the driving mechanism in and out of engagement for in and out of alignment with their intermeshing gears for the purpose of obtaining forward and reverse drives. It has also been known in the past to utilize constant mesh transmissions in which pairs of gears are in constant meshing engagement and are selectively rendered operative by coupling selective gears with a shaft of the transmission to which other gears are secured. A typical constant mesh transmission will utilize a plurality of clutches placed to engage one clutch from one pair of gears while disengaging the other clutches for each of the other pairs of meshed gears so that only one constantly engaged gear between the input and output shaft is connected to the power through the input shaft by a clutching member for that gear.
The present invention has for one of its objects a constant intermeshed gear transmission which simplifies the changing of gears so that only one gear of predetermined ratio is powering the output shaft at any one time and which drive gear can be shifted to a second drive gear without the benefit of plural actuated clutches.
Typical prior art constant mesh transmissions can be seen in U.S. Pat. No. 2,117,654 to Cotanch for a Power Transmission Mechanism of the variable speed type having multiple forward speeds and a reverse drive and which employs gears constantly intermeshed in all of the driving mechanisms and in U.S. Pat. No. 4,640,145 to Vandervoort for a Multiple Countershaft Transmission which has an improved multiple substantially identical countershaft assembly change gear transmission having two countershafts. In the Sturmer patent, U.S. Pat. No. 3,691,861, a basic multi-stage constant mesh transmission mechanism is provided which can be used with an automatic transmission as well as a manual transmission in which the input unit has two input shafts and a main clutch for connecting the gears selectively to a drive shaft. In the Cunningham patent, U.S. Pat. No. 1,513,694, a transmission is provided which allows a change speed gearing for motor vehicles in which the speed change gearing utilizes constantly meshing gears. In the Wolkoff patent, U.S. Pat. No. 2,243,548, a power transmission is provided in which the different speed gears are always in mesh and power is transmitted from the input shaft to the output shaft by means of selected clutches and in which a braking mechanism controls the clutch operating mechanism. In the Quick patent, U.S. Pat. No. 4,398,432, a vehicle transmission has a power shifting and overrunning clutch to selectively provide a multiple speed transmission to provide shifting on the go. In the Storle patent, U.S. Pat. No. 1,735,187, a transmission for motor driven vehicles provides for shifting the driving connection between two shafts from one shaft of gears of different ratio. The Spangler patent, U.S. Pat. No. 1,717,632, is a speed changing transmission in which the gears are not shifted but rather the clutch mechanisms for the various speeds and for the reverse gear are operated by the driver according to the manner in which he wishes to operate the vehicle. In the Cataldo patent, U.S. Pat. No. 4,597,304, a multi-speed power transmission has an input shaft and a coaxially aligned output shaft and each shaft has gearing members connected to it. Selectively engagable clutch mechanisms are used to selectively connect respective ratio gear shafts to change the gear ratio. The Windsor-Smith et al. patent, U.S. Pat. No. 4,464,947, is an automatic transmission for city buses and the like which uses a constant mesh multiple layshaft type gear train. The Sumiyoshi patent, U.S. Pat. No. 4,565,106, is a gear transmission mechanism for automotive vehicles, such as passenger cars, in which each of one of a pair of gears is a fixed gear which is fixed to a shaft on which it is mounted and the other gear is an idler gear which is selectively operated by a gear engaging system to rotationally couple the idler gear to the shaft on which it is mounted to thereby engage the gear.
The present invention is directed towards a constantly meshed gear transmission in which a plurality of driver ratios are accomplished through a plurality of different size gears, one of each pair of gears being fixedly attached to an output shaft while each of the gears connected to the input shaft acts as an idler gear until that gear is engaged to thereby operate the transmission at that gear ratio and which transmission allows for the smooth shift from one idler gear to another to engage each gear sequentially to change the gear ratio of the transmission.